Why are you sure? You could mention some marginal Vedic topics first and then get to Krsna in a roundabout, non-pushing way. If not, even the fact that you're a devotee and others notice it is preaching.

Sometimes when you can't preach directly, just being an intelligent gentlleman is preaching under such circumstances of social obligations. After all, you put up with your wife who only partly follows. Surely you must have to entertain her with a lot of prajalpa as well no? (No offense meant, it is just a fact of life.)

In my experience, such obligations are what you make them. It's up to you. You can sit passively and go through the motions and regret every second of it or you can take control of the direction of the conversation and make it an enlivening evening. Speak about spiritual or such related topics according to their level and what will touch them. It's enlivening for them and you. You never know, you might learn some things from such a devout Muslim. You could even start a private conversation with him about strictly following your faith where family members or social circumstances hinder your practice. You never know, he may be in a similar position as you and you might find you have more in common with him than your wife!

there is direct way of preaching and the indirect one

direct is by trying to convince them to follow vaishnav path and indirect is to give them prasad,darshan of your dieties ,have them smell offered incense etc.

indirect is also preaching.

you can also help them become better devotees in the context of their own religion(while stuffing them with prasad)

you can learn a little bit about the Islam (essence is the same as KC) and try to uplift them by talking about the humility and tolerance of Muhammad a.s.:

“A Bedouin urinated in the mosque, and the people got up to sort him out. The Messenger of Allaah (peace and blessings of Allaah be upon him) said to them, ‘Leave him alone, and throw a bucket of water over it. You have been sent to make things easy for people, not to make things hard.’ ” (Fath, 6128).

you can teach the your Muslim neighbor about what his books say about eating beef :

Hadith on Milk, Ghee and Beef

This comes from the famous hadith collection Zâd al-ma‘âd by Ibn Qayyim. I have been all through the many hadith books and I have never found any saying that the Prophet of Islam, peace be upon him, ate beef. In fact, he advised against it. If this guidance from the Prophet would be better known, then it could really help to ease the tensions between Hindus and Muslims over the beef issue, if the Muslims would leave off eating beef on the advice of their own Prophet. Let there be peace and harmony between Hindus and Muslims, peace and harmony in the whole world. I wish that could come true!

First, the hadith in the original Arabic:

‘an suhayb radiya Allâh ‘anhu yarfa‘uhu:
‘alaykum bi-laban al-baqar fa-innahâ shifâ' wa-samnuhâ dawâ' wa-lahmuhâ dâ'.

The Urdu translation:

hazrat suhaib raziyallâhu ‘anh se rivâyat hai keh huzûr-e akram sallá Allâh ‘alaihi va-sallam ne farmâyâ:
"gâ'î kâ dûdh isti‘mâl karnâ lâzim pakaR lo, kyû n keh us me n shifâ hai, aur us ke ghî me n davâ kî tâ s îr hai, aur us ke gosht me n rog hai."

Free translation in English:

The Prophet, peace be upon him, said:
"You should use cows' milk, because it is good for health, and cows' ghee is good for health, but beef is bad for health."

Actually, the literal meaning of the words the Prophet used is much stronger than that. He said that milk is "healing," ghee is "medicine," and beef is "disease."

Urdu commentary by Hafiz Nazr Ahmad:

mustadrak-e hakîm kî kitâbuttibb me n pahlî hadî s yeh hai keh rasûlullâh sallallâhu ‘alaihi va-sallam ne farmâyâ, "allâh ne ko'î bîmârî nahî n utârî jis kî davâ nah utârî ho, aur gâ'î ke dûdh me n har bîmârî se shifâ kî tâ s îr hai." us kitâb kî tîsrî hadî s me n shifâ kî vajah yeh farmâ'î, "kyûnkeh gâ'î har dirakht se cartî hai -- fa-innahâ tarummu min kull shajar."


In the Book of Medicine of the Mustadrak al-Hakîm [a classical hadith commentary by al-Hakîm al-Nîsaburî], the first hadith is: The Messenger of Allah, peace and blessings upon him, said: "Allah did not create any disease without creating its cure; and in cows' milk is a cure for every disease." The third hadith in this book says on the subject of healing: "Because the cow grazes from every kind of plant."

It is a fact that, compared to that of camels, buffaloes, sheep, goats, and all other animals, cows' milk is superior. It is free from everything harmful and provides healing for various illnesses. The butter and ghee from cows' milk are a treatment for several more diseases. Physicians prescribe it as medicine. On the other hand, beef is hot in nature, and its heat causes some diseases to occur.

This hadith and commentrary were published in a book called Tibb-i nabavî by Hâfiz Na z r Ahmad (Dihlî: Varld Islâmik Pablikeshanz, 1982), p. 226.